As a mobile communication antenna capable of coping with a plurality of frequency bands, a dielectric patch antenna disclosed in JP-A-2001-60823 is known. In FIG. 1, a dielectric patch antenna 1 is constituted in that a first patch antenna electrode 3 of the length a and a second patch antenna electrode 4 of the length b spaced apart are formed on one surface of the plate-shaped dielectric block 2 that is the base and that a ground electrode 5 that is the ground of the dielectric patch antenna 1 is formed on the bottom surface. By a feeding pin 6 that is an input/output terminal of the dielectric patch antenna 1, the dielectric patch antenna 1 is connected to a first feeding line 9 on a substrate 8 where the dielectric patch antenna 1 is mounted. Further, according to a feeding pin 7 that is a second input/output terminal, it is connected to a second feeding line 10 on the substrate 8.
When such a signal of the frequency band f1 as the length a of the patch antenna electrode 3 can be about half of the propagated wavelength within the dielectric block 2 is entered from the feeding pin 6 into the dielectric patch antenna 1, the patch antenna electrode 3 is oscillated, hence to emit a radio wave. At a receiving time, the patch antenna electrode 3 is oscillated by an incident radio wave of the frequency band f1, hence to supply a receiving signal from the feeding pin 6.
Similarly, when such a signal of the frequency band f2 as the length b of the patch antenna electrode 4 can be about half of the propagated wavelength within the dielectric block 2 is entered from the feeding pin 7 into the dielectric patch antenna 1, the patch antenna electrode 4 is oscillated, hence to emit a radio wave. At a receiving time, the patch antenna electrode 4 is oscillated by an incident radio wave of the frequency band f2, hence to supply a receiving signal from the feeding pin 7.
In the above conventional antenna, since holes are bored in the substrate 8 to feed a signal to the antenna 1 through the feeding pins 6 and 7, the surface mounting on the substrate 8 is difficult.
Since the feeding pin 6 is disposed outside of the antenna electrode 3, the input impedance of the antenna 1 in the frequency f1 becomes high. It is necessary to provide the antenna with a separate match circuit in order to match with, for example, the 50Ω system, and this match circuit deteriorates the efficiency of the antenna 1.
Further, it is necessary to provide it with a feeding port for every frequency band, and a plurality of cables are required in the structure of separating the antenna 1 from a radio unit and in order to connect the both by one cable, a circuit for integration is additionally required.